From Patent Document 1, there is known a vehicle control system configured to determine target traveling positions one after another based on an actual traveling position of a main work vehicle and then to control a sub work vehicle toward each target traveling position. With this vehicle control system, there are disclosed a control mode for causing the sub work vehicle to follow the main work vehicle in such a manner to maintain offset amounts in the X (longitude) direction and the Y (latitude) direction which have been set relative to the main work vehicle, and a further control mode for causing the sub work vehicle to follow the main work vehicle along a traveling path which is obtained as a target traveling path by parallel shifting the traveling path of the main work vehicle by a working width amount, and so on.
The “follow-up” control according to Patent Document 1 is designed for a work in a large and wide-open work land, not for a ground work in such a work land as a field having a relatively small area bordered by a ridge. In the case of a ground work in such a work land (field), in particular a ground work for agricultural production, the work load will be divided into a central work land traveling in which straight work traveling and U-turn are effected in repetition in a central region (central work land) of the work land, and a headland traveling for effecting a work in and along a headland work traveling region (called “headland”) delimited by/along the circumference of the central work land, and the ground work will be effected separately for these divided works. For this reason, the central work and the headland work land will be preliminarily divided into a central work land and a headland. And, different controlling operations are required between the central work land traveling and the headland traveling.
Execution of a ground work such as a cultivating work for the central work land traveling and the headland traveling by a single unmanned work vehicle is known from e.g. Patent Document 2. However, merely combining the control configurations such as those disclosed in Patent Document 1 and Patent Document 2, under a work vehicle coordinating control operatively linking a main work vehicle and a sub work vehicle, may not provide effective realization of the central work land traveling consisting mainly of straight traveling and the headland traveling involving complicated turns.